This invention concerns the catalytic combustion of fuel downhole in an oil well. Through the use of downhole combustors, steam can be generated downhole and injected into the reservoir to displace heavy oil from the reservoir. The present combustor is compact so that it can fit into an oil well.
Any mixture of fuel and air, no matter how long its heating value, will burn if it is preheated to a sufficiently high temperature. If the mixture is burned over a catalyst, a lower preheat temperature is required, and this is why catalysts are used to burn mixtures having a low heat value. With or without a catalyst, preheating is usually done by exchanging heat from the combustion gas to the incoming fuel-air mixture. Some systems operate in such tight confines that it is difficult to include a heat exchanger.
My U.S. Pat. No. 4,445,570, the disclosure of which is incorporated by reference herein, describes a downhole steam generator having a catalytic air preheater. The air preheater transfers heat from the combustion gas, through a metal wall, to the incoming fuel-air mixture. The design is compact, but intricate. The catalytic combustor of the present invention is simpler and does the same job.